Moore and Common Sense

Seminar 1

PHIL2120 Topics in Analytic Philosophy

21 September 2012

1

Reading for this seminar

Required reading:

Soames, Ch 1, Ch 2 pp. 12-23

(See course website)

Optional reading:

Moore ‘Proof of the External World’

(See course website)

2

Biography

George Edward Moore

Born 1873 in London

Entered Cambridge University 1892

Worked at Cambridge University 1896-1939

Together with Frege, Russell and Wittgenstein, is seen as one of the founders of analytic philosophy

3

Outline

1. Moore’s general views on common sense

2. Moore’s proof of the external world

4

Common sense

Moore is famous as a great defender of common sense.

Moore claimed that he knew with certainty a number of propositions about himself and others, and that we know with certainty analogous propositions about ourselves and others

These propositions are the propositions of common sense .

5

Examples of the common sense propositions Moore claimed to know

1a. That he had a human body which was born at certain time in the past 1b. That he coexisted with other living human bodies that had been born in the past 1c. That the earth had existed for many years before his body was born 1d. That he was a human being who had many experiences of different types 1e. That other human bodies were the bodies of human being who had experience of a similar type as himself 2. That very many human beings and known corresponding propositions about themselves and others

6

Philosophy and common sense

Moore: The propositions of common sense constitute the starting point of philosophy and can’t be overturned by philosophical argument.

Other philosophers: i) Many philosophers have denied that we can

know some or all of the propositions Moore claimed were common sense.

ii) Some philosophers (including Moore’s mentors) have claimed to know that some of these common sense propositions are false.

7

Examples of philosophical views incompatible with Moore’s common

sense propositions

i) Temporal Anti-realism: time is unreal

ii) Monism: Only one thing exists

iii) Idealism: Everything is mental (nothing exists external to every mind)

8

Why should we agree with Moore?

One reason: It is very hard to disagree with Moore and be consistent

Indeed Moore claimed that there has never been a philosopher who has denied common sense propositions and being consistent

9

Problem with this reason

Just because it is hard to consistently deny Moore’s common sense propositions doesn’t show that they are true, or known to be true.

Perhaps the fact that it is hard to consitently deny them is just a fact about human limitations.

10

A better reason

• When we have a conflict between philosophical views such as temporal anti-realism or monism or idealism, we have a conflict between: speculative philosophical principle vs the most basic convictions of common sense

• In cases such conflict, we should reject the principles we have less confidence in

• Since we have more confidence in the propositions of common sense, we should reject the speculative philosophical principles

11

Philosophy turned on its head

Moore:

• The job of philosophy is not to prove or refute the propositions of common sense

• Instead, the job of philosophy is to explain how we know the propositions of common sense

12

An important case: External world skepticism vs common sense

External world skepticism: We cannot know that objects that are external to all our minds exist

Def: An object is external to all our minds iff it is conceptually possible for x to exist without anyone perceiving or experiencing it

Def: It is conceptually possible that p iff it is not possible to know that not p purely on the basis of reasoning

13

An important case: External world skepticism vs common sense (cont)

Examples of external objects: hands, chairs, tables

External world skepticism is incompatible with a number of common sense propositions

14

Descartes’s Dreaming Argument

Premise 1: I do not know that I am not dreaming

Premise 2: If I do not know that I am not dreaming then I do not know that I have hands

Conclusion: I do not know that I have hands

Note: ‘I have hands’ can be replaced by any other sentence about external objects

15

Moore’s proof of an external world

Premise 1: Here (holding up one hand) is one hand

Premise 2: here (holding up his other hand) is another hand

Conclusion 1: Therefore there are at least two hands

Conclusion 2: Therefore there are at least two things external to our minds

16

Moore’s argument that he has given a proof

The argument is a proof since it satisfies the following conditions:

i) The conclusion is different from the premises

ii) The conclusion follows from the premises (necessarily, if the premises are true, the conclusion is true)

iii) The premises are known to be true

17

Moore’s argument that knows he has hands when he holds up his hands

i) It is obvious that he knows he has hands, just as it is obvious that you know you are hearing my words

ii) Comparision with proof of misprints on a page

a) Disagreement about misprints

b) Settled by pointing that out

c) We would be perfectly happy to accept such a proof in real life

d) But if we can know that there are three misprints in this way, then Moore knows he has hands when he looks at them

18

The skeptic’s response

Facts about what we would ordinarily be happy with excepting are irrelevant since it might be that what we ordinarily say is wrong

The skeptic has a powerful argument that we don’t know we at hands, and this argument also shows that we do not know that there are 3 misprints on a page either

Moore has done nothing to reduce the force of this argument

19

Soames’s defense of Moore’s proof

Moore’s reply to the skeptic’s response is in effect to:

i) Ask for a justification for the claim that we don’t know that we have hands, and

ii) Claim that any attempted justification will rely on a theory of knowledge that is less certain than the common sense proposition that we know that we have hands

20

Example of a theory of knowledge that the skeptic might rely on

K1) In order to know that p one must have evidence that conceptually entails p

K2) If E is part of our evidence then we couldn’t possibly be mistaken about it

While Moore accepts that K1 and K2 have some intuitive plausibility, he claims that they aren’t as certain as the proposition that we know we have hands

21

Where the skeptic goes wrong according to Moore

• The skeptic assumes that we can be certain about what knowledge is before we decide whether paradigm cases of knowledge are genuine

• But this is backward! We are more certain that some paradigm cases of knowledge are genuine than we are about the nature of knowledge.

• Indeed in constructing a theory of knowledge, one fundamental test is that it be consistent with our common sense knowledge about cases of knowledge

22

The real job of philosophy according to Moore

• The job philosophers of knowledge is not to prove or refute that we have hands

• Rather, it is to construct a theory of knowledge that is i) consistent with obvious cases of knowledge, and ii) explains how such knowledge arises

23